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United States Patent |
5,076,217
|
Clough
|
December 31, 1991
|
Engine cooling systems
Abstract
A cooling system for an engine having a cylinder block defining a plurality
of cylinders and a cylinder head mounted on the cylinder block, includes a
pump having an outlet which is connected, at one end of the engine to a
cooling jacket of the cylinder block, the cooling jacket of the cylinder
block being connected at the other end of the engine to a cooling jacket
of the cylinder head and an outlet being provided from the cooling jacket
of the cylinder head at said one end of the engine; the cooling jacket of
the cylinder head defining a plurality of passageways extending
longitudinally of the cylinder head, said passageways being arranged to
conduct coolant to different parts of the head portion of each cylinder,
the passageways merging intermediate of the cylinders.
Inventors:
|
Clough; Malcolm J. (Bedworth, GB)
|
Assignee:
|
Jaguar Cars Limited (GB)
|
Appl. No.:
|
707641 |
Filed:
|
May 30, 1991 |
Foreign Application Priority Data
Current U.S. Class: |
123/41.74; 123/41.82R |
Intern'l Class: |
F02F 001/14 |
Field of Search: |
123/41.74,41.82 R,193 H,41.08
|
References Cited
U.S. Patent Documents
3203408 | Aug., 1965 | Winkleman | 123/41.
|
3385273 | May., 1968 | Baster | 123/41.
|
4175503 | Nov., 1979 | Ernest | 123/41.
|
4730579 | Mar., 1988 | Yamada et al. | 123/41.
|
Foreign Patent Documents |
646201 | Nov., 1950 | GB.
| |
Primary Examiner: Kamen; Noah P.
Attorney, Agent or Firm: Davis, Bujold & Streck
Claims
I claim:
1. A cooling system for an engine including a cylinder block defining a
plurality of cylinders and a cylinder head mounted on the cylinder block,
said cooling system comprising a pump having an outlet which is connected,
at one end of the engine, to a cooling jacket of the cylinder block, said
cooling jacket of the cylinder block being connected to a cooling jacket
of the cylinder head at the other end of the engine and an outlet being
provided from the cooling jacket of the cylinder head at said one end of
the engine, the cooling jacket of the cylinder head defining a plurality
of passageways extending longitudinally of the cylinder head, said
passageways being arranged to conduct coolant to different parts of the
head portion of each cylinder, the passageways merging intermediate of the
cylinders.
2. A cooling system according to claim 1 in which the passageways defined
by the cooling jacket of the cylinder head conduct coolant to; the
underside of the exhaust ports; the upperside of the exhaust ports; the
underside of the inlet ports; and at least one side of the sparking plug
boss.
3. A cooling system according to claim 1 in which the cooling jacket of the
cylinder head includes at least one transverse passageway per cylinder,
said transverse passageway interconnecting two of the longitudinally
extending passageways.
4. A cooling system according to claim 3 in which the cross-sectional areas
of the longitudinal passageways on either side of the transverse
passageway are varied to induce flow of coolant along the transverse
passageway.
5. A cooling system according to claim 1 in which the cooling jacket of the
cylinder block is connected to the cooling jacket of the cylinder head via
a single transfer port.
6. A cooling jacket according to claim 1 in which the cooling jacket of the
cylinder head is additionally connected at said other end of the engine,
directly to the outlet of the pump via a bypass.
7. A cooling system according to claim 6 in which the bypass is formed as
an integral part of the cylinder block. end of the engine to an outlet at
the other end of the engine.
8. A cooling system according to claim 6 in which the outlet from the
cooling jacket of the cylinder block is connected to the bypass and then
via a transfer passage to the cooling jacket of the cylinder head.
9. A cooling system according to claim 6 in which means is provided in the
bypass to control the rates of flow of coolant through the bypass and
through the cooling jacket of the cylinder block.
10. A cooling system according to claim 9 in which the means for
controlling the rate of flow through the bypass and through the cooling
jacket of the cylinder block is adjustable.
11. A cooling system according to claim 9 in which the means for
controlling the rate of flow of coolant through the bypass is located
downstream of a connection of the cooling jacket of the cylinder block to
the bypass.
12. A cooling system according to claim 1 in which cylinder liners are
located in bores in the cylinder block, the cooling jacket of the cylinder
block being defined by annular chambers around the upper portions of the
cylinder liners, the annular chambers being interconnected to provide a
passage from the inlet at one end of the engine to an outlet at the other
end of the engine.
Description
BACKGROUND TO THE INVENTION
The present invention relates to engine cooling systems and in particular
to cooling systems for internal combustion engines.
In conventional internal combustion engines coolant is fed to the engine
block at the front and passes to the cylinder head via transfer holes
associated with each of the cylinders. These transfer holes must be
correctly sized, in order to achieve even cooling throughout the engine.
In such systems, the coolant normally exits at the front of the cylinder
head and consequently, coolant velocities at the rear of the cylinder head
will be less than those at the front, since coolant will collect towards
the front of the engine. To effectively control component temperature,
coolant should be directed towards the areas which experience the greatest
heat flow. These are, for a four valve per cylinder pent roof engine, the
spark plug region and exhaust and inlet valve bridges. Thus, for
conventional cooling, the lower flow rates at the rear of the cylinder
head have to be catered for without compromising other cooling effects
such as delivery of coolant between the exhaust valve bridge from the
transfer holes.
In such systems, a cross flow technique is normally used in which portions
of the coolant flow are directed separately to each cylinder.
Consequently, in order to control component temperatures using coolant
velocity, either a large overall flow rate or very small passage sizes
need to be employed. There are restraints on the size of pump that may be
used to circulate the coolant and consequently it is desirable that small
coolant passage sizes should be used. Such small size passages have
however to be cast or machined, neither of which are desirable in terms of
water jacket core rigidity or cost.
The present invention overcomes these problems by directing the full flow
of coolant from end to end along the cylinder head to cool all the
cylinders.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, a cooling system for an
engine including a cylinder block defining a plurality of cylinders and a
cylinder head mounted on the cylinder block comprises a pump having an
outlet which is connected, at one end of the engine, to a cooling jacket
of the cylinder block, said cooling jacket of the cylinder block being
connected to a cooling jacket of the cylinder head at the other end of the
engine and an outlet being provided from the cooling jacket of the
cylinder head at said one end of the engine, the cooling jacket of the
cylinder head defining a plurality of passageways extending longitudinally
of the cylinder head, said passageways being arranged to conduct coolant
to different parts of the head portion of each cylinder, the passageways
merging intermediate of the cylinders.
The end to end flow of coolant through the cooling jacket of the cylinder
head in the invention described above, will enable greater control of the
coolant velocities throughout the engine and in particular in the cylinder
head and as all the coolant flows past all the cylinders, improved
temperature distribution is achieved over each cylinder portion as well as
along the length of the cylinder head, compared to that of conventional
design. Furthermore, as the full flow of coolant passes through the
cooling jacket of the cylinder head, high velocities may be achieved
without adopting passageways of a very small cross-sectional area.
Although the pump pressure in such cooling systems will be high, as there
is only one transfer passage between the cylinder block and cylinder head
as opposed to two or more transport holes per cylinder in the conventional
cooling system, there are fewer sealing problems between the cylinder
block and cylinder head. Merging of the passageways intermediate of the
cylinder head permits transfer of heat within the coolant flowing
therethrough, again improving temperature distribution.
Preferably coolant enters the cooling jacket of the cylinder head through a
single transfer port, the transfer port dividing into a plurality of
passageways which conduct the coolant to:
a) the underside of the exhaust ports, cooling the combustion chamber and
exhaust ports;
b) the upper side of the exhaust ports, cooling the exhaust ports and the
exhaust valve guide bosses;
c) the underside of the inlet ports, cooling the combustion chamber; and
d) either side of the sparking plug boss.
Cooling between the exhaust valve seats and, if necessary, the inlet valve
seats may be achieved by transverse passages interconnecting the passages
which extend longitudinally from end to end of the cylinder head. Flow of
coolant may be encouraged through these transverse passages by providing
suitable restrictions in the longitudinal passages.
The cylinder block requires less coolant than the cylinder head and thus
less coolant flow is required in the cooling jacket or cylinder block.
According to a preferred embodiment of the invention, the cooling jacket of
the cylinder block may additionally be connected, at said other end of the
engine, directly to the outlet of the pump via a bypass. By this means
excess coolant is diverted past the cooling jacket of the cylinder block
by the bypass. The bypass may be external of the engine or may be an
integral channel cast into the cylinder block. The proportion of coolant
flowing through the block and through the bypass may be controlled by a
fixed or variable restriction.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of the invention is now described, by way of example only,
with reference to the accompanying drawings, in which:
FIG. 1 illustrates diagrammatically an engine with cooling system in
accordance with the present invention;
FIG. 2 illustrates in sectional plan view the cooling jacket of the
cylinder block of the engine illustrated in FIG. 1;
FIG. 3 illustrates a section along the line III--III of FIG. 2;
FIG. 4 shows the diagrammatic coolant flow scheme of the cylinder head for
one cylinder of the engine illustrated in FIG. 1;
FIG. 5 shows a diagrammatic detail of the coolant flow scheme illustrated
in FIG. 4;
FIG. 6 illustrates diagrammatically in sectional plan view part of the
cylinder head with the coolant flow scheme; and
FIGS. 7 to 11 show sections of the cylinder head taken along the lines A to
E of FIG. 6.
DESCRIPTION OF A PREFERRED EMBODIMENT
As illustrated in FIG. 1, an internal combustion engine 10 comprises a
cylinder block 11 having a cylinder head 12 bolted thereto. An engine
driven cooling pump 13 has an inlet 14 for coolant which is connected to a
radiator (not shown) in conventional manner. The outlet 15 from the pump
13 is connected at the front of the engine 10 to the cooling jacket 16 of
the cylinder block 11 by inlet 17 and to a bypass 18, said bypass 18
running the length of the engine 10.
As illustrated in FIGS. 2 and 3, cylinder liners 20 are located in bores 21
in the cylinder block 11. The upper portion 22 of each of the liners 20 is
spaced from the cylinder block 11 to provide an annular chamber 23
thereabout, the annular chamber 23 being interconnected to provide a
passage from the inlet 17 at the front of the engine 10 to an outlet 24 at
the rear of the engine 10. Alternatively the cooling jacket of the
cylinder block may be defined by passages cast into the block itself.
The outlet 24 from the cooling jacket 16 at the rear of the engine 10, is
connected to the bypass 18 and then via a transfer passage 25 and an inlet
26 to a cooling jacket 27 of the cylinder head 12, at the rear of the
engine 10.
A control valve 30 is located in the bypass 18 downstream of the connection
thereof to the outlet 24. The control valve 30 may be controlled by
suitable means, for example a thermostat at the outlet 24, to control the
rate of flow of fluid through the bypass 18 and hence the cooling jacket
16.
As illustrated in FIGS. 4, 5 and 6, the cooling jacket 27 of the cylinder
head 12 comprises a series of longitudinally extending passages 35 to 39
through which coolant will flow past each cylinder 41 from the inlet 26 at
the rear of the engine 10 to an outlet 40 at the front of the engine 10.
The flow scheme illustrated in FIGS. 4 to 6 is for a four valve pent roof
cylinder configuration. Passage 35 takes coolant around the outside of the
exhaust ports 42; passage 36 takes coolant between exhaust ports 42 and
spark plug boss 43; passage 37 takes coolant between the spark plug boss
43 and inlet ports 44; passage 38 takes coolant around the outside of the
inlet ports 44; and passage 39 takes coolant over the top of the exhaust
ports 42 and around the exhaust valve guides 45, as illustrated in FIGS. 9
and 10. Between the cylinders 41, the passages 35 to 38 merge into a
single passageway as illustrated in FIG. 11.
As illustrated in FIG. 4, a transverse passage 46 is provided between
passages 35 and 36, across the bridge 47 between the exhaust ports 42. A
further transverse passage 48 may also be provided between passages 37 and
38 across the bridge 49 between inlet ports 44, if required.
In order to induce flow of coolant through the passage 46, the
cross-sectional area of passage 35 is reduced downstream of passage 46
while the cross-sectional area of passage 36 is increased downstream of
passage 46, as illustrated in FIG. 6 and FIGS. 7, 8 and 9. A similar
technique would be used with passages 37 and 38, if transverse passage 48
were included.
A further advantage of the cooling system in accordance with the present
invention is that the absence of transfer holes between each cylinder will
enable the bolt bosses 50 to be moved inwardly and also extended to
provide means of draining the lubricating oil from the valve gear by
drilled or cored holes 51. Moving the bolt bosses 50 inwardly in this
manner will reduce the volume of coolant required and also stiffen the
cylinder head.
The outlet 40 from the cooling jacket of the cylinder head 12 at the front
of the engine 10, is connected to the inlet 14 of the pump 13 via the
radiator (not shown) in conventional manner and a thermostatically
controlled bypass may be provided between the outlet 40 and inlet 14 of
the pump 13, to bypass the radiator until the coolant reaches its
operating temperature.
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